Contaminants migrating from unengineered facilities, accidental spills, and industrial operations threaten health and ground water supply. Such contamination often covers large volumes of soil underlying several acres of surface area. In view of the high cost of land, limited resources, and the fact that contamination can occur in densely populated or industrialized areas, there exists a need to find new, economical, and efficient technologies of remediation for rapid reclamation and rehabilitation of such sites.
Coupling between electrical, chemical, and hydraulic gradients is responsible for different types of electrokinetic phenomena in soils. In electro-osmosis, the pore fluid moves due to the application of a constant, low DC current by electrodes inserted in soil. In the five decades since its first application in 1947, electro-osmosis has been used in applications such as (1) improving stability of excavations, (2) increasing pile strength, (3) stabilization of fine-grained soils, (4) dewatering of foams, sludges, and dredgings, (5) groundwater lowering and barrier systems, (6) chemical grout injection, (7) removal of metallic objects from the ocean sea bottom, (8) decreasing pile penetration resistance, (9) increasing petroleum production, (10) determination of volume change and consolidation characteristics of soils, (11) removal of easily water-soluble salts from agricultural soils, and (12) separation and filtration of certain materials in soils and solutions.
None of the prior art in electro-osmosis resulted in successful and consistent decontamination of soils. The prior art references encountered premature precipitation of contaminants due to basic conditions created in the soil surrounding the cathode. The prior art also teaches away from adding water to the soil during electro-osmosis, much of the emphasis of the prior electro-osmosis work being on dewatering soils to consolidate or stabilize them.